"Social media and Facebook are mentioned a lot, in a variety of ways. I have seen couples who battle over Facebook posts: who is argued to be showing greater investment in the relationship and who is not, as a result of posts," she says.

"This sort of example is one enactment of broader issues about insecurity, the individual (sometimes couple) need for external validation."

Ms Shaw, a clinical and counselling psychologist, says there are also battles about Facebook as a bigger argument about computer versus couple time.

"I have had couples say 'you communicate more on Facebook with your friends than you do with me …', so the focus being outside the relationship rather than in it," she says.

There is the issue of privacy versus publicity with "couples disagreeing about these levels of comfort".

And she's had "many examples" where an infidelity is exposed on Facebook to shame and humiliate another in public.

Social or anti-social? You decide. Picture: AP

Australian Family Lawyers Melbourne head lawyer Melissa Muir says the firm has clients who have found out about their partner's affairs via Facebook.

"People have found love letters via Messenger."

She says Facebook is also a useful tool in obtaining evidence against individuals in family law proceedings.

"If someone has posted a photo of themselves with a new motorbike or car but claim they don't have any money or assets or are on holiday and say they don't have money to support children, it can be used against them," Ms Muir says.

Her advice: "Don't put anything on Facebook. Around the time of separation shut it down".

In recent years, US and UK studies have found divorces resulted from social media-related disagreements.

A study, published in the Journal of Cyberpsychology, Behavior and Social Networking, found that people who use Facebook more than once an hour are more likely to "experience Facebook - related conflict with their romantic partners."

You’ve been warned: Family lawyers use Facebook to gather evidence against you in court.

In 2012, Divorce-Online UK surveyed British divorce lawyers to determine if there was an anecdotal link between social media use and divorce.

According to that survey, approximately one in three divorces resulted from social media-related disagreements.

Similarly, a 2010 survey by the American Academy of Matrimonial Lawyers (AAML) found that four out of five lawyers used evidence derived from social networking sites in divorce cases, with Facebook leading the pack.

Ms Shaw says it's important for couples to discuss privacy and publicity about their relationship, and who they are comfortable sharing what with.

The terms of this are better agreed than unilaterally decided.

"Facebook is an important and efficient form of communication about family, but can also provide a public space to enact betrayals, air family disagreements and disputes, and then it can become a weapon and source of considerable distress," she says.

"Who owns couple or family material is really important to get clear, and to make sure to sensitively manage the boundaries set. Just because others boundaries may be looser, ultimately how you manage your own relationship conveys the respect, sensitivity, privacy and consideration you want available between the two of you."

TIPS FOR COUPLES ON FACEBOOK

Together decide on:

- What role you want social media to play in your relationship and communication with others;